The present invention generally relates to reproducing apparatuses capable of performing high-speed reproduction of a video signal recorded on tracks formed obliquely with respect to the longitudinal direction of a magnetic tape, and more particularly to a reproducing apparatus capable of performing high-speed reproduction of a video signal by use of a simple circuit construction requiring few adjustments, by commonly using a frequency-voltage converter within a servo circuit which controls the speed of a motor, during a high-speed reproduction, normal reproduction, and the like.
A helical scan type recording and reproducing apparatus has been known conventionally, for recording and reproducing a video signal on and from a magnetic tape. In such a recording and reproducing apparatus, the video signal is recorded along tracks formed obliquely with respect to the longitudinal direction of the magnetic tape by rotary video heads, upon recording. Moreover, a control pulse having a predetermined period is recorded on a control track formed along the longitudinal direction of the magnetic tape by a stationary control head. Among this type of recording and reproducing apparatuses, there are apparatuses capable of obtaining a high-speed reproduction picture in which the movement in the picture is considerably quick compared to the movement in a normal reproduction picture. The high-speed reproduction is performed by reproducing the video signal by the rotary video heads in a state where the magnetic tape is caused to travel in the same direction as upon recording or in the opposite direction at a speed in the order of ten times the tape speed upon recording or normal reproduction. During this high-speed reproduction, a desired recording position of the video signal recorded on the magnetic tape is searched and detected at a high speed, by monitoring the high-speed reproduction picture.
During the above high-speed reproduction, the pressing contact between a capstan and a pinch roller is released, for example, to cause the magnetic tape to travel at a high speed by the rotational force of a reel motor. Here, the magnetic tape must always travel at a constant speed, regardless of the length or amount of magnetic tape wound around the reel. Thus, during the high-speed reproduction, the control pulse reproduced from the control track is supplied to a frequency-voltage converter wherein the control pulse is converted into a voltage in accordance with the tape traveling speed. This voltage from the frequency-voltage converter is applied to the reel motor, to control the rotational speed of the reel motor so that the control pulse is reproduced with a predetermined period.
If a head servo circuit for controlling the rotational speed of the rotary video heads to a constant speed is operated in the same manner as upon normal reproduction, the rotational speed of a drum motor which rotates a rotary body mounted with the rotary video heads becomes equal to the rotational speed upon normal reproduction. On the other hand, because the tape traveling speed upon high-speed reproduction is in the order of ten times the tape traveling speed upon normal reproduction, the relative linear speed between the tape and the heads becomes different from that upon normal reproduction. Accordingly, the reproduced video signal frequency and the reproduced horizontal scanning frequency deviate from predetermined values, and horizontal synchronism cannot be obtained in the television receiver.
Therefore, in the conventional apparatus, a phase control loop within the above head servo circuit was disconnected upon high-speed reproduction, and simultaneously, the reproduced horizontal synchronizing signal was supplied to a frequency-voltage converter. Hence, the reproduced horizontal synchronizing signal was converted into a voltage in accordance with the reproduced horizontal synchronizing signal frequency at the frequency-voltage converter, and an output voltage of this frequency-voltage converter was applied to the above drum motor. Accordingly, the rotational speed of the drum motor was controlled so that the reproduced horizontal synchronizing signal frequency became a predetermined value (for example, 15.734 kHz upon recording and reproduction of an NTSC system color video signal). As a result, the rotational speed of the drum motor became faster than the rotational speed upon normal reproduction, during a high-speed reproduction in which the tape is caused to travel in the same direction as upon recording. On the other hand, the rotational speed of the drum motor became slower than the rotational speed upon normal reproduction, during a high-speed reproduction in which the tape is caused to travel in a direction opposite to that upon recording.
However, the above frequency-voltage converter supplied with the reproduced control pulse and the frequency-voltage converter supplied with the reproduced horizontal synchronizing signal, respectively are used only during the high-speed reproduction. Thus, the circuit construction became complex and uneconomical. Further, because both the frequency-voltage converters must be adjusted, there was a disadvantage in that the adjustments were troublesome to perform and time consuming.